Preheat the oven to 350°F. Lightly grease a large casserole or 3-4 quart baking dish and set aside. Combine shredded and grated cheeses in a large bowl and set aside.
Cook the pasta in salted water one minute shy of al dente. Remove from the water, strain, and place in a large bowl.
Drizzle pasta with extra virgin olive oil and stir to coat the pasta. Set aside to cool while preparing the cheese sauce. Add the cut broccoli rabe and porchetta cubes to the cooled pasta and stir to fully incorporate.
Melt the butter in a deep saucepan, dutch oven or stock pot.
Whisk in the flour over medium heat and continue whisking for about one minute until bubbly and golden.
Gradually whisk in the milk and half and half (or heavy cream) until nice and smooth. Continue whisking until you see bubbles on the surface and then continue cooking and whisking another 2 minutes.
Add 1/3 of the all the combined cheeses and whisk until smooth. Add the other 1/3 of combined cheeses and continue whisking until creamy and smooth. The sauce should be nice and thick.
Stir in the cooled pasta until combined and the pasta is fully coated into the cheese sauce.
Pour half the mac and cheese into the prepared baking dish. Top with the remaining 1/3 of the combined cheeses and then the remaining mac and cheese. Add salt and pepper to taste.
In a small bowl, combine the panko crumbs, additional grated Locatelli Romano, melted butter and crushed red pepper, if desired. Sprinkle over the top and bake until bubbly and golden brown, about 30 minutes. Serve immediately.